Răspuns:
Explicație:
1. a.
a≠0
b:a=2 rest 3
b=2a+3
c=4a
[tex]\frac{a}{c} =\frac{a}{4a} =\frac{1}{4} =0,25[/tex]
25% din c reprezinta a
b. a+b+c=87
a+2a+3+4a=87
7a=84
a=12
b=24+3=27
c=48
2. E(x)=(5x+1)(x+6)+(x+1)(x-1)(x²+1)-(x²+2)²-30x
E(x)=5x²+31x+6+(x²-1)(x²+1)-x⁴-4x²-4-30x
E(x)=x²+x+2-x⁴+x⁴-1
E(x)=x²+x+1
E(n)=n²+n+1=(n+1)²-n
(n+1)²-n<(n+1)²
n²+n+1>n², deoarece n>0
Deci avem relatia adevarata
n²<E(n)<(n+1)²
